Spiral arm

The center of the Milky Way extends out and surrounds the four main spiral arms of the center

synonym NomaArm (Moment arm) generally refers to spiral arm

Spiral arm, also known as Outer arm , moment arm or swan - moment arm, from the galaxy One of the four main spiral arms that extend outward from the center and surround the center. Swan arm Extends outward from the radius of 15.5 ± 2.8Kpc to Perseus arm outside.

Its name comes from earth Observation is through Cygnus Because of. Due to the gravity changes in local areas, spiral arms of different shapes have been formed in different areas, and a large number of star clusters can be found in some areas. " NomaArm 'It's the part of the swan's arm near the center of the Milky Way.

Chinese name: Spiral arm
Alias: Outer arm 、 Moment arm or swan - Moment arm
Start: the galaxy core

Origin: earth observation
Swan arm: Radius 15.5 ± 2.8Kpc extended to Perseus arm
Different: Gravity variation

catalog

one brief introduction
two Track parameters

brief introduction

Announce

edit

Galaxy yes sunlight There are many similar or same type galaxies in the universe. These galaxies have a large number of stars and form relatively flat disks under the action of gravity. The disk keeps rotating, and there are more stars in the center than in the outer edge, moving at a higher speed. As a result, stars form spiral arms when viewed from above or below outside the galaxy.

Track parameters

Announce

edit

Spiral arm

The Milky Way is earth and sunlight The galaxy to which it belongs. It is named after the bright band whose main part is projected on the celestial sphere, which is called the Milky Way in China. The discovery of the Milky Way has gone through a long process. After the invention of the telescope, Galileo First, we observed the Milky Way with a telescope and found that the Milky Way is composed of stars. then, T. Wright 1. Kant J. H. Lambert and others believe that the Milky Way and all fixed star It may assemble into a huge star system.

In the late 18th century, F. W. Herschel made Reflecting telescope He started the observation of star counting to determine the structure and size of the star system. He asserted that the star system was in the shape of a flat disk, and the sun was not far from the center of the disk. After his death, his son J F. Herschel inherited his father's career, continued to conduct in-depth research, and expanded the work of star counting to the southern sky.

At the beginning of the 20th century, astronomers called the star system with the Milky Way as the apparent phenomenon the Milky Way. J. C. Captan used statistical parallax method to determine the average distance of stars, combined with star counting, and obtained a model of the Milky Way Galaxy. In this model, the sun is in the middle, and the Milky Way Galaxy is a disk with a diameter of 8000 seconds and a thickness of 2000 seconds. H. Sapril measured Globular cluster From the distribution of globular clusters to study the structure and size of the Milky Way. His model is that the Milky Way is a lenticular star system, and the sun is not at the center. Shapley concluded that the diameter of the Milky Way is 80 thousand seconds away, and the sun is 20 thousand seconds away from the silver center. These values are too large because Shapley did not include interstellar extinction when calculating distance. In the 1920s, after the discovery of the rotation of the Milky Way, Shapley's model of the Milky Way was recognized.

The Milky Way is a giant Spiral galaxy ， Sb type, with 4 swivel arms in total. It contains 100 to 200 billion stars. The Milky Way as a whole rotates poorly. The rotation speed at the sun is about 220 km/s. The sun revolves around the silver center for about 250 million years. The visual absolute magnitude of the Milky Way is - 20.5. The total mass of the Milky Way is about 1 trillion times the mass of our sun and about 10 times the total mass of all stars in the Milky Way. This is strong evidence for the existence of dark matter in our Milky Way galaxy that extends far beyond bright star disks. With regard to the age of the Milky Way, the current mainstream view is that the Milky Way was born shortly after the big bang of the universe. Using this method, we can calculate that the age of our Milky Way is about 14.5 billion years old, with errors of more than 2 billion years. The scientific community believes that the "Big Bang" of the birth of the universe may happen

The Milky Way is the star system where the solar system is located, including 120 billion stars and a large number of star clusters, nebulae, as well as various types of interstellar gas and dust. Its total mass is 140 billion times that of the sun. Most stars in the Milky Way are concentrated in a flat sphere shaped like a discus. The protruding part in the middle of the oblate sphere is called the "nuclear sphere", with a radius of about 7000 light years. The middle of the nuclear sphere is called the "silver core", and the four sides are called“ Silver plate ”。 There is a larger sphere outside the silver disk, where there are few stars and the density is small, called the "silver halo", with a diameter of 70000 light-years. The Milky Way is a Spiral galaxy , with vortex structure, that is, there is a silver center and two spiral arms, which are 4500 light years apart. The rotation speed and period of each part of the silver core are different due to the distance from the center. The sun is about 23000 light years away from the center of the silver and rotates around the center of the silver at a speed of 250 km/s, with a period of about 250 million years.

Spiral arm

About 90% of the matter in the Milky Way is concentrated in stars. There are many kinds of stars. According to the physical properties, chemical composition, spatial distribution and motion characteristics of stars, stars can be divided into five star families. The youngest extreme family I stars are mainly distributed on the spiral arms in the silver disk; The oldest extreme family II stars are mainly distributed in the silver halo. Stars often cluster together. In addition to a large number of binary stars, more than 1000 star clusters have been found in the Milky Way. There are also gas and dust in the Milky Way, which account for about 10% of the total mass of the Milky Way. The distribution of gas and dust is uneven, some of them are gathered as nebulae, and some are scattered in interstellar space.

Since the 1960s, a large number of interstellar molecules, such as CO H2O, etc. Molecular clouds are the main sites for star formation. The core of the Milky Way Galaxy, the silver core or core, is a very special place. It emits strong radio and infrared, X-ray and gamma radiation. Its nature is not clear, there may be one Giant black hole It is estimated that its mass may be tens of millions of times that of the sun. Little is known about the origin and evolution of the Milky Way.

1971 britain Astronomers Linden Bell and Martin Ness analyzed the infrared observation and other properties of the central region of the Milky Way, pointed out that the energy of the central region of the Milky Way should be a black hole, and predicted that if their hypothesis was correct, a very small source of radio radiation could be observed in the center of the Milky Way, and the nature of this radiation should be consistent with that of people on the ground synchrotron The same radiation properties are observed in. Three years later, such a source was found, which was Renma A. Centaur A has a very small scale, which is only the size of an ordinary star. The radio radiation intensity emitted is 2 * 10 (34th power) ergs/second,

It lies within 0.2 light years of the galactic dynamical center. There are moving ionized gases with a speed of up to 300 km/s around it, and there are also strong Infrared radiation source 。 It is known that the activities of all stellar objects can not explain the strange characteristics of Renma A. Therefore, Renma A seems to be the best candidate for massive black holes. However, since there is no conclusive evidence for massive black holes at present, astronomers are cautious to avoid referring to massive black holes in conclusive language. Our Milky Way contains about 200 billion stars, including more than 100 billion stars, of which the sun is a typical one. The Milky Way is a rather large spiral galaxy, which has three main components: the silver disk containing the spiral arms, the silver center of the central projection and the halo part.

The spiral arms are the regions of the vortex and rod vortex clusters that extend from the core of the galaxy. These long and thin regions are similar to whirlpools, hence the name of such galaxies. The existence of the spiral arm once made scientist I was puzzled because when the galaxy rotates fixed star It moves faster than a star near its center. In fact, spiral arms are not the result of star motion, but density waves can lead to star formation. Therefore, the spiral arm is bright because of the young stars (and the originally massive and bright stars do not live long), not because of the motion of the stars.

NASA recently released a picture 32 million away from the earth Light year Faraway spiral galaxy The Hubble Space Telescope captured this spectacular picture of the spiral galaxy, which resembles our Milky Way. The image taken from the Hubble Space Telescope shows that this code named "Messier 74" gives an incredible picture. The dotted spiral arms rotate from the core, forming a "spectacular pattern" similar to the "wheel of Catherine".

A bright pink area is clearly visible around the swivel arm. These are hydrogen Due to the heat from the surrounding young stars, the huge nebula of. The dusty matter in the galaxy is dragged from the core of the galaxy to the tail of the spiral arm. “ Messier 74 ”Located in the direction of Pisces, it is about 32 million light years away from the earth.

It is better than Galaxy Slightly smaller, it is composed of about 100 billion stars. "Messier 74" galaxy was France It was first discovered by astronomer Pierre Meixiang and later incorporated into another French astronomer Charles Messier Table of deep space objects. "Messier 74" emits very weak light, which is difficult for amateur telescopes to find, so it is nicknamed "phantom galaxy" by astronomers. The new photo is in hubble space telescope Based on many images taken from 2003 to 2005, a small missing area in the picture was supplemented by data from the Gemini North Telescope in Hawaii.

Novice on the road

Growth task Getting Started with Editing Edit Rule Edit by myself

I have questions

Content query Online Service Official post bar Feedback

Complaints and suggestions

Report bad information Failed to appeal through entries Complaint of infringement information Blocking query and unblocking

Jinggong Network Anbei No. 1100000200001